Fiber-optic transmission makes use of the wavelength division multiplexing (WDM) technique. As with any multiplexing technique, this technique consists in combining, over a given medium, a plurality of modulated signals. In the case of optical communication, the medium is none other than an optical fiber conveying signals in different channels. These channels are defined by the carrier wavelength of the transmitted signals. Wavelength multiplexing, which will be referred to as WDM below, requires high-quality signal emission. The need for high-quality signal emission increases as wavelengths are brought closer together. Specifically, a shift in the wavelength of an emitted signal may produce various edge effects. For example, such a shift many lead to interference with a signal at a neighboring wavelength. It also causes problems on reception, especially during the demultiplexing step. Similarly, the quality of the components used directly impacts the quality of the processing and, therefore, the usable distances or passbands. Specifically, the bandwidth of a line connected to a demultiplexer especially depends on the quality of the components in charge of the filtering allowing a signal at a given wavelength to be extracted. At the present time, obtainable manufacturing tolerances are a bandwidth-limiting factor.